90 research outputs found
Three-magnon problem for exactly rung-dimerized spin ladders: from general outlook to Bethe Ansatze
Three-magnon problem for exactly rung-dimerized spin ladder is brought up
separately at all total spin sectors. At first a special duality transformation
of the equation is found within general outlook. Then
the problem is treated within Coordinate Bethe Ansatze. A straightforward
approach is developed to obtain pure scattering states. At values S=0 and S=3
of total spin the equation has the form inherent in the
chain. For solvability holds only in five previously found {\it
completely integrable} cases. Nevertheless a partial S=1 Bethe solution always
exists even for general non integrable model. Pure scattering states for all
total spin sectors are presented explicitly.Comment: 38 page
Electronic and transport properties of rectangular graphene macromolecules and zigzag carbon nanotubes of finite length
We study one dimensional (1D) carbon ribbons with the armchair edges and the
zigzag carbon nanotubes and their counterparts with finite length (0D) in the
framework of the H\"{u}ckel model. We prove that a 1D carbon ribbon is metallic
if its width (the number of carbon rings) is equal to . We show that the
dispersion law (electron band energy) of a 1D metallic ribbon or a 1D metallic
carbon nanotube has a universal {\it sin-}like dependence at the Fermi energy
which is independent of its width. We find that in case of metallic graphene
ribbons of finite length (rectangular graphene macromolecules) or nanotubes of
finite length the discrete energy spectrum in the vicinity of
(Fermi energy) can be obtained exactly by selecting levels from the same
dispersion law. In case of a semiconducting graphene macromolecule or a
semiconducting nanotube of finite length the positions of energy levels around
the energy gap can be approximated with a good accuracy. The electron spectrum
of 0D carbon structures often include additional states at energy
, which are localized on zigzag edges and do not contribute to
the volume conductivity.Comment: 6 pages, 5 figure
An improved adsorption method for the characterization of water-based supercapacitor electrodes
The specific surface area is a key characteristic of carbon materials used in supercapacitor electrodes. In this paper, the use of a methylene blue technique for specific surface area determination is presented. Values for the specific surface area, determined by a new method, provide better correlation with theoretical values for the specific electrical capacity of highly-porous carbon electrodes than the values measured by the common BET method. Additionally, the methylene blue adsorption method is thought to characterize carbon adsorption activity in relation to a supercapacitor electrolyte
Integrable boundary conditions for classical sine-Gordon theory
The possible boundary conditions consistent with the integrability of the
classical sine-Gordon equation are studied. A boundary value problem on the
half-line with local boundary condition at the origin is considered.
The most general form of this boundary condition is found such that the problem
be integrable. For the resulting system an infinite number of involutive
integrals of motion exist. These integrals are calculated and one is identified
as the Hamiltonian. The results found agree with some recent work of Ghoshal
and Zamolodchikov.Comment: 10 pages, DTP/94-3
The Zakharov-Shabat spectral problem on the semi-line: Hilbert formulation and applications
The inverse spectral transform for the Zakharov-Shabat equation on the
semi-line is reconsidered as a Hilbert problem. The boundary data induce an
essential singularity at large k to one of the basic solutions. Then solving
the inverse problem means solving a Hilbert problem with particular prescribed
behavior. It is demonstrated that the direct and inverse problems are solved in
a consistent way as soon as the spectral transform vanishes with 1/k at
infinity in the whole upper half plane (where it may possess single poles) and
is continuous and bounded on the real k-axis. The method is applied to
stimulated Raman scattering and sine-Gordon (light cone) for which it is
demonstrated that time evolution conserves the properties of the spectral
transform.Comment: LaTex file, 1 figure, submitted to J. Phys.
Experimental Substantiation of New Presentation Form of Cholera Diagnostic Sera
Objective of the study is experimental substantiation of possibility to produce new presentation form of cholera diagnostic sera – lyophilizate in bottles. Materials and methods. Cholera diagnostic sera. Liophylization was performed in Martin Christ Epsilon 2-6D. Residual moisture of dry sera was determined using humidity meter Sartorius MA 150. Solubility of experimental samples was assessed visually. pH was evaluated by potentiometry with the help of PK SevenExcellence-475 Mettler Toledo device, measuring pH/ORP/Ion content/conductivity/concentration. Specific activity and specificity was analyzed through expanded agglutination reaction, using relevant control strains of cholera vibrio. Results and conclusions. Experimentally justified is the possibility to lyophilize cholera diagnostic sera in flasks. Specified are the optimum parameters of lyophilization. It is determined that lyophilization does not result in deterioration of properties, as judging by the quality indicators they meet the requirements of regulatory documentation. Using accelerated aging test, it is demonstrated that the new presentation form of cholera diagnostic sera – lyophilizate in flasks – maintains their specific activity within five years term (the set out shelf life), which fully conform to normative standards
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